The invention relates to a device for sealing the gap between the inlet end of a rotary kiln and a stationary inlet housing.
In view of the great lengths of modern rotary kilns and taking account of the considerable differences in temperature between the operating state and the cold state of such a furnace installation, considerable changes in position of the inlet end of the rotary kiln, caused by thermal expansion, occur on transition from the operating state to the cold state and vice versa. The exhaust gases extracted at the inlet end of the rotary kiln are usually used in a heat exchanger arranged in front of the rotary kiln for preheating the raw material, and therefore satisfactory sealing of the gap between the inlet end of the rotary kiln and the stationary inlet housing must be ensured in order to prevent the infiltration of air there. Such sealing must be ensured not only after the normal warm operating state has been reached, but also on starting up of the furnace which is still essentially cold.
It has been shown in practice that this requirement is not fulfilled satisfactorily by the known arrangements. In the known arrangements the sliding ring is to some extent axially movable and is pushed in the direction towards the inlet end of the rotary kiln by a cylinder which is operated by a pressure medium. However, if the variation in position of the rotary kiln is particularly great (resulting from a great furnace length), the clearance of motion of the sliding ring in the known arrangements is not sufficient to keep the two wearing surfaces (one of which is borne by the sliding ring and the other by the ring which rotates with the rotary kiln) in sufficiently close contact to form a seal even when the furnace installation is in the cold state, and thus at the particularly critical time of restarting the furnace.
An increase in the length of the stationary ring, and with it a corresponding increase in the movability of the sliding ring, is, on the other hand, very difficult to achieve from the design point of view, since this would have a very unfavourable effect on the construction of the inlet chute which delivers the material to the rotary kiln (by reducing the angle of inclination of this chute).
The object of the invention, therefore, is to avoid these disadvantages of the known constructions and to provide a device of the type described above which is distinguished by a particularly large range of movement of the sliding ring and which ensures satisfactory sealing of the gap between the inlet end of the rotary kiln and the stationary inlet housing even in the case of very long rotary kilns in the cold state.